@putout/plugin-typescript

TypeScript is JavaScript with syntax for types.

(c) typescriptcriptlang.org

????Putout plugin adds ability to transform TypeScript code. Enabled by default for ts and tsx files.

Install

npm i putout @putout/plugin-typescript -D

Rules

✅ apply-as-type-assertion;
✅ apply-type-guards;
✅ apply-utility-types;
✅ convert-commonjs-to-esm;
✅ convert-esm-to-commonjs;
✅ convert-generic-to-shorthand;
✅ convert-namespace-to-global;
✅ cts-file;
✅ find-file;
✅ mts-file;
✅ remove-duplicate-exports;
✅ remove-duplicate-interface-keys;
✅ remove-duplicates-from-union;
✅ remove-unused-types;
✅ remove-getter-arguments;
✅ remove-setter-return-type;
✅ remove-useless-mapped-types;
✅ remove-useless-mapping-modifiers;
✅ remove-useless-non-null-expressions;
✅ remove-useless-parens;
✅ remove-useless-promise;
✅ remove-useless-types;
✅ remove-useless-types-from-constants;
✅ rename-file-cts-to-ts;
✅ rename-file-mts-to-ts;

Config

{
    "rules": {
        "typescript/apply-as-type-assertion": "on",
        "typescript/apply-utility-types": "on",
        "typescript/apply-type-guards": "on",
        "typescript/convert-generic-to-shorthand": "on",
        "typescript/convert-commonjs-to-esm": "off",
        "typescript/convert-esm-to-commonjs": "off",
        "typescript/convert-namespace-to-global": "off",
        "typescript/remove-duplicates-from-union": "on",
        "typescript/remove-duplicates-interface-keys": "on",
        "typescript/remove-duplicates-exports": "on",
        "typescript/remove-useless-types-from-constants": "on",
        "typescript/remove-unused-types": "on",
        "typescript/remove-useless-types": "on",
        "typescript/remove-useless-parens": "on",
        "typescript/remove-useless-promise": "on",
        "typescript/remove-getter-arguments": "on",
        "typescript/remove-setter-return-type": "on",
        "typescript/remove-useless-mapped-types": "on",
        "typescript/remove-useless-non-null-expressions": "on",
        "typescript/cts-file": "off",
        "typescript/mts-file": "off",
        "typescript/rename-file-cts-to-ts": "off",
        "typescript/rename-file-mts-to-ts": "off",
        "typescript/find-file": ["off", {
            "ignore": []
        }]
    }
}

apply-as-type-assertion

According to best practice.

❌ Example of incorrect code

const boundaryElement = <HTMLElement>e.target;

✅ Example of correct code

const boundaryElement1 = e.target as HTMLElement;

apply-utility-types

❌ Example of incorrect code

type SuperType1 = {
    [Key in keyof Type]?: Type[Key];
};

✅ Example of correct code

type SuperType1 = Partial<Type>;

apply-type-guards

It just so happens that TypeScript has something called a type guard. A type guard is some expression that performs a runtime check that guarantees the type in some scope.

(c) typescript.org

Check out in ????Putout Editor.

❌ Example of incorrect code

const isNumber = (a) => typeof a === 'number';

✅ Example of correct code

const isNumber = (a): a is number => typeof a === 'number';

convert-generic-to-shorthand

There is no difference at all. Type[] is the shorthand syntax for an array of Type. Array<Type> is the generic syntax. They are completely equivalent.

(c) https://stackoverflow.com/a/36843084/4536327

Convert generic to shorthand.

❌ Example of incorrect code

interface A {
    x: Array<X>;
    y: Array<X | Y>;
}

✅ Example of correct code

interface A {
    x: X[];
    y: X[] | Y[];
}

Comparison

Linter	Rule	Fix
???? Putout	`typescript/convert-generic-to-shorthand`	✅
⏣ ESLint	`@typescript-eslint/array-type`	✅

convert-commonjs-to-esm

Checkout in ????Putout Editor.

❌ Example of incorrect code

import foo = require('foo');
export = 5;

✅ Example of correct code

import foo from 'foo';

export default 5;

convert-esm-to-commonjs

Checkout in ????Putout Editor.

❌ Example of incorrect code

import foo from 'foo';

export default 5;

✅ Example of correct code

import foo = require('foo');
export = 5;

convert-namespace-to-global

Checkout in ????Putout Editor.

❌ Example of incorrect code

declare namespace global {
    var al: any;
}

✅ Example of correct code

declare global {
    var al: any;
}

Comparison

Linter	Rule	Fix
???? Putout	`typescript/convert-namespace-to-global`	✅
⏣ ESLint	`@typescript-eslint/no-namespace`	❌

remove-duplicates-from-union

❌ Example of incorrect code

type x =
    | boolean[]
    | A
    | string
    | A
    | string[]
    | boolean[];

✅ Example of correct code

type x =
    | boolean[]
    | A
    | string
    | string[];

remove-duplicate-exports

In JavaScript duplicate exports leads to SyntaxError, anyways TypeScript parses such code and reports Duplicates Identifier diagnostic.

It gives us ability to automate fixing of such code ????. Check it out in ????Putout Editor.

❌ Example of incorrect code

export {
    a,
    hello,
    a,
    world,
};

✅ Example of correct code

export {
    hello,
    a,
    world,
};

☝️ The rule fits good with putout/add-newlines-between-specifiers of eslint-plugin-putout.

remove-getter-arguments

The get syntax binds an object property to a function that will be called when that property is looked up

(c) MDN

❌ Example of incorrect code

export interface IParamsConstructor {
    get [fromArray](name: string): IParams;
}

✅ Example of correct code

export interface IParamsConstructor {
    get [fromArray](): IParams;
}

remove-setter-return-type

The set syntax binds an object property to a function to be called when there is an attempt to set that property.

(c) MDN

❌ Example of incorrect code

export interface IParamsConstructor {
    set fromArray(values: ParamsArray): string;
}

✅ Example of correct code

export interface IParamsConstructor {
    set fromArray(values: ParamsArray);
}

remove-useless-types-from-constants

❌ Example of incorrect code

const x: any = 5;

✅ Example of correct code

const x = 5;

remove-unused-types

❌ Example of incorrect code

type n = number;
type s = string;

const x: n = 5;

✅ Example of correct code

type n = number;

const x: n = 5;

remove-useless-types

❌ Example of incorrect code

type oldType = {
    a: number;
    b: string;
};
type newType = oldType;

const x: newType = {
    a: 5,
    b: 'hello',
};

✅ Example of correct code

type oldType = {
    a: number;
    b: string;
};

const x: oldType = {
    a: 5,
    b: 'hello',
};

remove-useless-parens

Check it out in ????Putout Editor.

❌ Example of incorrect code

const m: X[] = [];
const z: X | Y = 5;
const f: X = 5;

✅ Example of correct code

const x: X[] | Y[] = [];
const m: X[] = [];
const z: X | Y = 5;
const f: X = 5;

remove-useless-promise

Check it out in ????Putout Editor.

❌ Example of incorrect code

function doStuff(): Promise<string> {
    return 'hello';
}

✅ Example of correct code

function doStuff(): string {
    return 'hello';
}

remove-useless-mapped-types

Remove useless mapped types.

❌ Example of incorrect code

type SuperType = {
    [Key in keyof Type]: Type[Key];
};

✅ Example of correct code

type SuperType = Type;

remove-useless-non-null-expressions

Checkout in ????Putout Editor.

❌ Example of incorrect code

const bar = foo!!.str;
const baz = bar!?.n;

✅ Example of correct code

const bar = foo!.str;
const baz = bar?.n;

remove-useless-mapping-modifiers

Remove useless mapping modifiers.

❌ Example of incorrect code

type SuperType = {
    [Key in keyof Type]+?: Type[Key];
};

✅ Example of correct code

type SuperType = {
    [Key in keyof Type]?: Type[Key];
};

remove-duplicate-interface-keys

❌ Example of incorrect code

interface Hello {
    hello: any;
    hello: string;
}

✅ Example of correct code

interface Hello {
    hello: string;
}

cts-file

Run convert-esm-to-commonjs for all *.cts files with help of redlint.

Check out in ????Putout Editor.

mts-file

Run convert-esm-to-commonjs for all *.mts files with help of redlint.

Check out in ????Putout Editor.

find-file

Checkout in ????Putout Editor.

❌ Example of incorrect code

__putout_processor_filesystem(['/', [
    '/hello.ts',
    'const a: number = 5;',
]]);

✅ Example of correct code

__putout_processor_filesystem(['/', [
    '/hello.ts',
    'const a = 5;',
]]);

rename-file-cts-to-ts

Rename *.cts files when type === "commonjs":

 /
 |-- package.json
 `-- lib/
-     `-- hello.cts
+     `-- hello.ts

Check out in ????Putout Editor.

rename-file-mts-to-ts

Rename *.mts files when type === "module":

 /
 |-- package.json
 `-- lib/
-     `-- hello.mts
+     `-- hello.ts

Check out in ????Putout Editor.

License

MIT

Current Tags

13.0.2 ... latest (3 months ago)

@putout/plugin-typescript

Install

Rules

Config

apply-as-type-assertion

❌ Example of incorrect code

✅ Example of correct code

apply-utility-types

❌ Example of incorrect code

✅ Example of correct code

apply-type-guards

❌ Example of incorrect code

✅ Example of correct code

convert-generic-to-shorthand

❌ Example of incorrect code

✅ Example of correct code

Comparison

convert-commonjs-to-esm

❌ Example of incorrect code

✅ Example of correct code

convert-esm-to-commonjs

❌ Example of incorrect code

✅ Example of correct code

convert-namespace-to-global

❌ Example of incorrect code

✅ Example of correct code

Comparison

remove-duplicates-from-union

❌ Example of incorrect code

✅ Example of correct code

remove-duplicate-exports

❌ Example of incorrect code

✅ Example of correct code

remove-getter-arguments

❌ Example of incorrect code

✅ Example of correct code

remove-setter-return-type

❌ Example of incorrect code

✅ Example of correct code

remove-useless-types-from-constants

❌ Example of incorrect code

✅ Example of correct code

remove-unused-types

❌ Example of incorrect code

✅ Example of correct code

remove-useless-types

❌ Example of incorrect code

✅ Example of correct code

remove-useless-parens

❌ Example of incorrect code

✅ Example of correct code

remove-useless-promise

❌ Example of incorrect code

✅ Example of correct code

remove-useless-mapped-types

❌ Example of incorrect code

✅ Example of correct code

remove-useless-non-null-expressions

❌ Example of incorrect code

✅ Example of correct code

remove-useless-mapping-modifiers

❌ Example of incorrect code

✅ Example of correct code

remove-duplicate-interface-keys

❌ Example of incorrect code

✅ Example of correct code

cts-file

mts-file

find-file

❌ Example of incorrect code

✅ Example of correct code

rename-file-cts-to-ts

rename-file-mts-to-ts

License

Current Tags

46 Versions